1. Field of the Invention
The present invention relates to improvements in air volume characteristics of axial fans.
2. Description of the Related Art
Along with sophistication of performance, recent electronics generate increasingly large amounts of heat from electronic components disposed inside the electronics. Fan devices are used along with these electronics in order to minimize hot air retention inside a housing and to discharge the hot air from inside the housing to the outside. In order to achieve good performance of the electronics, cooling inside the housing is essential.
Many electronic components are disposed inside of the housing of an electronic device. In this case, the large number of electrical components create a resistance in the flow passage of an airflow inside the housing. A fan device produces a maximum amount of air volume when the flow passage resistance is zero. Conversely, a fan device produces a minimum amount of air volume when the flow passage of the fan device is completely blocked due to the flow passage resistance. Since the fan device is under load because of the flow passage resistance in the electronic device, an actual air volume obtained is small when compared with the maximum air volume.
Two types of fan devices are primarily used in electronics: centrifugal fans and axial fans. Centrifugal fans provide high static pressure and are able to produce a given air volume stably even when the flow passage resistance within the housing is high. Centrifugal fans, however, produce smaller air volumes than axial fans. However, axial fans cannot provide as much static pressure as that of centrifugal fans, but the axial fans can produce greater air volumes.
An axial fan is chosen in cases where a large air volume is required to cool the inside of the housing of an electronic device. Axial fans are frequently used nowadays as a cooling unit for electronics.
Accordingly, there is a need for an improvement in air volume characteristics in an intermediate static pressure zone, i.e., the flow passage resistance, in an axial fan, in cases when an axial fan is used as a cooling unit for an electronic device. So far, attempts have been made to improve air volume characteristics through modifications of the shapes of blades in the axial fans.